Updated docs, and created helper method for Radial Distance

README.md

@@ -162,3 +162,46 @@ $reducedPoints = $reducer->reduce($threshold, $lookAhead);
 The original polygon of 2151 points has been reduced to 293.
 
 ![Lang example](http://emcconville.com/point-reduction-algorithms/examples/dayton_Lang.svg)
+
+### Zhao-Saalfeld
+
+Added in version `1.2.0`.
+
+```php
+use PointReduction\Common\Point,
+    PointReduction\Algorithms\ZhaoSAalfeld;
+$givenPoints = array(
+    new Point(-84.158640, -39.822480),
+    new Point(-84.159250, -39.820120),
+    // ... and so one
+);
+$degree = 7;
+$lookAhead = 7;
+$reducer = new ZhaoSAalfeld($givenPoints);
+$reducedPoints = $reducer->reduce($degree, $lookAhead);
+```
+
+The original polygon of 2151 points has been reduced to 1493.
+
+![Zhao-Saalfeld example](http://emcconville.com/point-reduction-algorithms/examples/dayton_ZhaoSaalfeld.svg)
+
+### Radial Distance
+
+Added in version `1.2.0`.
+
+```php
+use PointReduction\Common\Point,
+    PointReduction\Algorithms\RadialDistance;
+$givenPoints = array(
+    new Point(-84.158640, -39.822480),
+    new Point(-84.159250, -39.820120),
+    // ... and so one
+);
+$tolerance = 0.0025;
+$reducer = new RadialDistance($givenPoints);
+$reducedPoints = $reducer->reduce($tolerance);
+```
+
+The original polygon of 2151 points has been reduced to 449.
+
+![Radial Distance example](http://emcconville.com/point-reduction-algorithms/examples/dayton_RadialDistance.svg)

src/Algorithms/RadialDistance.php

@@ -46,6 +46,12 @@
  */
 class RadialDistance extends Abstraction
 {
+    /**
+     * Tolerance property to compare radial distance.
+     * @var double
+     */
+    private $_tolerance = 0.0;
+
     /**
      * Remove points with a distance under a given tolerance.
      *
@@ -55,13 +61,12 @@ class RadialDistance extends Abstraction
      */
     public function reduce( $tolerance )
     {
+        $this->_tolerance = $tolerance;
         $sentinelKey = 0;
         while ($sentinelKey < $this->count()-1) {
             $testKey = $sentinelKey + 1;
             while ( $sentinelKey < $this->count()-1
-                && $this->distanceBetweenPoints($this->points[$sentinelKey],
-                                                $this->points[$testKey]) < $tolerance )
-            {
+                && $this->_isInTolerance($sentinelKey, $testKey) ) {
                 unset($this->points[$testKey]);
                 $testKey++;
             }
@@ -70,4 +75,21 @@ public function reduce( $tolerance )
         }
         return $this->reindex();
     }
+
+    /**
+     * Helper method to ensure clean code.
+     *
+     * @param integer $basePointIndex    Sentinel point index.
+     * @param integer $subjectPointIndex Test point index.
+     *
+     * @return bool True if subject point is under tolerance, false otherwise.
+     */
+    private function _isInTolerance($basePointIndex, $subjectPointIndex)
+    {
+        $radius = $this->distanceBetweenPoints(
+            $this->points[$basePointIndex],
+            $this->points[$subjectPointIndex]
+        );
+        return $radius < $this->_tolerance;
+    }
 }

tests/RadialDistanceTest.php

@@ -33,6 +33,7 @@ class RadialDistanceTest extends PHPUnit_Framework_TestCase
      * @test
      * @covers PointReduction\Algorithms\Abstraction::setPoints
      * @covers PointReduction\Algorithms\RadialDistance::reduce
+     * @covers PointReduction\Algorithms\RadialDistance::_isInTolerance
      * @covers PointReduction\Algorithms\Abstraction::lastKey
      * @covers PointReduction\Algorithms\Abstraction::count
      *